Display screen or portion thereof with a graphical user interface



The FIGURE is a front view of a display screen or a portion thereof witha graphical user interface of our new design.

The dashed broken line perimeter in the drawing illustrates a displayscreen or portion thereof and forms no part of the claimed design. Theremaining dashed broken lines in the drawing illustrate portions of thegraphical user interface that form no part of the claimed design.

CLAIM The ornamental design for a display screen or a portion thereofwith a graphical user interface, as shown and described herein.